Bolt mechanism for firearm



Jan. 1, 1957 original Filed Feb. 1, 195o 2 Sheets-SheerL W M @m5 w .Mm mw Il f /k 3 7 ,Y u l .N E M .w N10. V Y d. Il f E O n. @m v m l D 4 m@ Il z ||11 M911 8 n.. A Q. ON .Q ,3 on B .M 1.. Nw o@ @mem 0%@ A.. c@ -..Y |..H..|| w nrm I Mm.. mma 1N ..7 Z f f l I .vm I I. C/ um N9 .E ww ma ma @n ,w l! Q w d Y c 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1.1 111 1 1 1\l n @o E mn au Q. i wm E a. 47 .N|^h..|i|l1l|lN\Q .v 2L/QQ Il i mm .ILW on E y I Um! @N @n .H ...n.mll

Jan. 1, 1957 A. F; GAlDos Y BOLT MECHANISM FOR FIREARM Original Filed Feb. 1. 1950 2 Sheets-Sheet 2 grwamlo'o F'. El 1:1

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United States Patent t BOLT `MECHANISM FOR FIREARM Alonzo F. Gaidos, Redwood City, Calif.

Original application February 1, 1950, Serial No. 141,801. Divided and this application December 8, 1952, Serial No. 324,855

2 Claims. l(Cl. 42-16) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or `for the Government for governmental purposes without the payment of any royalty fthereon.

The present invention relates-to an improved bol-t and tiring pin mechanism for a lightweight automatic rille and moreV particularly -to the type of rifle as shown in my copending application, Serial No. 141,801, liled February 1, 1950 .and now matured into U. S. IPatent No. 2,688,203, of which this application is a division.

I-t is .an object of 4this invention to provide improved means for retaining an impact type of firing pin in `a reciprocalble bolt without interfering with the slide utilized to return the bolt to battery position.

The specific nature of this invent-ion .as well as other yobjects and advantages thereof will clearly yappear from .a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l -is `a fragmentary longitudinal `crosssectional view :of the receiver and bolt with `the l.striker in the cocked position; Y

Fig. 2 is a view .similar to Fig. l but in the tired position and :showing the means of attaching the barrel;

Fig. .3 is ,an enlarged cross-sectional View taken on line 13-13 of Fig. 4 showing the means of ejection;

lFig. 4 is a cross-'section view taken on line `4 4 of Fig. 1;

Fi-g. 5 is .an enlarged perspective view of the ejector;

Fig. 6 is .an enlarged view .of the extractor;

Fig. 7 is a fragmentary perspective view of the rear end of the bolt; Y

Fig. 8 is a perspective view of the firing pin retainer; and

Fig. 9 is a cross-sectional View taken on line 9 9 of Fig. 2.

The particular embodiment of the invention, tor the purpose of illustration as shown in the drawings, comprises Ia receiver 12, a bolt assembly 16, a breech block 114, -and an actuating bar U15.y

Receiver 1i2 is provided with a threaded longitudinal recess `16 in the upper rear end thereof to receive a striker retainer 17. The forward end of receiver 12 has a longi tudinal protruding cylindrical boss -18 with exterior lthreads 19 for a purpose which will be explained later.

A longitudinal bore 20 is provided in the upper lforward part of receiver `12. yextending out through boss 13 and axially disposed therewith to slidably receive :bolt assembly l13. Receiver 112 has a downwardly depending rectangular portion 21 being provided with `a vertically disposed magazine opening 22 to receive .a magazine 23. An angular slot 24 is `also provided in portion 2&1 rto receive breech lock '14 which `will be later described.

Extending :forwardly from threaded recess .16 of receiver '12 a longitudinal bore 2'5 is provided to receive -a striker 26. Forwardly of longitudinal bore 125 a small 2,775,835 Patented Jan. l, 1957 'ice bore 27 is provided to slidably support a reduced end 28 on striker 26. Forwardly of bore 27 and connected to bore 20, an enlarged recess 29 is provided Vto receive a buffer 30. On the forward upper right side .of receiver :112, .angularly disposed above the axis, is a longitudinal slot I31 to permity ejecti-on of a red round land for lthe accommodation of a bolt handle 32. On the rear `surface of receiver portion 21, a .transverse slot 33 is pro'- vided lto receive .a retainer 134 of :a bolt return spring rod 35. Rearwardly of .portion 21 a ldepending'lug 36 is provided -with a transverse slot 37, complementary to slot 33, to receiveaa retainer 38 on the rear end of rod 35. A bolt ret-urn helical spring 39 surroundsboltreturn spring rod 35 `for a purpose Ito lbe later described.

Striker 22'6 comprises an enlarged diametrical rear end 40 that is slidably mounted in bore 2.5 and provided with an angular projection 41 on the bottom end thereof, forming a hook for the engagement of sears that are notmore 4fully described as Ithey form no part of Ithis invention. Bore 2'5 is provided `with an opening in the bottom thereof to permit hook 41 to move therethrough :and therealong and also admit sears therein. A cylindrical recess 42 is provided in `the rear end of striker 26 to receive the forward end of a striker spring 43. Striker retainer 17 is provided `with -a cylindrical bore 44 oppositely disposed to recess 42 to receive the r'e-arrend of striker spring 43. Strikerretainer v17 is provided with a knurled cylindrical head 45 to permit .such retainer to lbe assembled 'in threaded recess 16.

A bolt 46 of bolt assembly 1-3, cylindrical in contour, is provided with a ltiringpin tunnel 47 therein to receive a 'firing pin 48 of `atconventional shape, and such bolt is reciprocable in bore 20. Firing pin spring 49 surrounds-pin 48 thereby biasing such pin rearwardly. Bolt 46 is provided on the rear `endithereof with lvertically positioned Lways S0 Yto receive a ring pin retainer 511. Firing pin 48 'has a reduced diametrical portion 520m the rear end thereof which is slidalbly received in a hole 53 of retainer 51. lBolt 46 is provided with a longitudinal dove-tailed slot '54 on the forward right side tangularly disposed above `the horizontal axis to receive bolt-handle 32. A `longitudinal ejector slot '55 with a semi-cylindrical bottom is provided oppositely :opposed-to slot '54-o`n1the left side of bolt `46 in the Iforward end thereof rto slidably receive an ejector 56.

Bolt `46 is provided with .a longitudinal shallow slot 57 rearwardly of and aligned with 1slot'54 .to receive a bolt handle strap '58. Strap '58 is provided with a protruding detent 59 'which nests in a recess l60 -therebyretaining bolt handle v32 in position. VRearwardly of and aligned with slot 5'5 -there is provided anejector stop clearance longitudinal slot 61 to permit the free movement of bolt 46 in bore 20 of receiver v12. In -the forward part of slot 55 rthere is provided a raised square lug 62 to limit the rearward movement of ejector 56. Ejector 56 has `an elongated longitudinal 'notch `63 arranged for slidable engagement of lug 62 in slot 55. Ejector 56 is urged rearwardly by -an ejector `spring 64 which is assembled in slot `55 between 4a rear surface `65 of lug 62 and a rear surface 166 of notch 63. Bolt 46 is provided ywith a transverse slot 67 .on the bottom rear end `to receive lock 14.

Bolt handle 32 has a depending 1arcuate handle portion 68 for manually operating bolt 46. A longitudinal rectangular slot 69 .is provided on bolt handle 3-2 to 'receive a spring-biased extractor 70 which `is pivotally `secured thereto by an extractor pin J71. Retainer `5l1 fis provided with a rectangularwopen slot 72 `on the bottom end thereof to permit Ia return bolt slide 7-3 to `contact bolt 46. Bolt return slide 73 is provided with a depending body portion 714 having -an axial hole 75 therein. Bolt return slide 73 is slidably mounted on bolt return spring rod 35 by means of hole 75. Bolt return slide 73 is biased forwardly by bolt return spring 39 thereby urging bolt '46 into the battery posi-tion. Lock 14 is provided `with `a rectangular open slot 76 angularly disposed on the left side thereof for a purpose Ito belater described.

The invention as illustrated employs a barrel 77 that is provided with annular ribs 78 equidistant apart to effect cooling of the barrel. The rear end of barrel 77 is of reduced diameter as shown at 79 to slidably be received in bore `20 of receiver 12. Forwardly of end 79 an enlarged diameter portion `80 is provided to be rotatably received in a recess l8l of a barrel n-ut 82. The rear end of barrel nut y82 is provided with a threaded recess 83 for securing barrel 77 to the receiver 1-2 through the medium of threads 19 on receiver 12. The rear portion of the enlarged diameter "80 is provided with a longitudinal -keyway 84 on the top and bottom thereof to receive a pair of keys `35 which `are also receivable in slots 86 of boss 18 of receiver 12 to properly ali-gn and position the barrel 77 in the receiver 12 and also to prevent rotation of such barrel and insuring the maintenance of predetermined head space.

Receiver `l2 is provided with vertically disposed ways y87 `on the fleft side thereof juxtaposed to slot 24 to slidably receive actuating bar 1'5 for reciprocating movement therein, Actuating 'bar 15 is provided with :oppositely disposed ribs S8 that lare receivable in ways 37 of receiver '12. A lock actuating stud `89 is provided in the center and protrudes to the right of actuating bar 15 tor a purpose to be described later. Oppositely disposed from stud 89, actuating bar 15 is provided with a lever 90 for manually operating lock 14 for a purpose to be described. lAn elongated longitudinal sl-ot 91 is provided on the left side vof a stock 92 to permit movement of lever 90 therealong. Receiver 12 is secured in `a stock 92 `by trigger guard 93. A forestock 94, pivotally mounted to a front bar-rel band (not shown), is secured to stock 92 by latching means 95. Forestock 94 is provided with a rectangular longitudinal slot opening 96 from the top on the rear end thereof to receive a barrel nut lock '97 which is secured to the bottom surface thereof by conventional wood screws. Barrel nut lock 97 lis provided with 'a resilient upstanding tooth 98 which cooperates lwith longitudinal serrations 99 on barrel nut S2 whereby such nut secures barrel 77 .at the proper head space in relation to bolt 46 and thereby secures such barrel to receiver 12. A narrow longitudinal slot 2100 is provided forwardly -of slot 96 in -forestock 94 to `accommodate a rod 101 that is coupled to actuating Ibar 1l5. Actuating bar 15 when c-oupled to rod 101 is springbias-ed rearwardly by spring means (not shown) thereby camming the lock 14 upwardly and locking the bolt 46 in the battery posit-ion and such bar is also actuated forwardly by gas pressure accumula-ting in an actuating cup (not shown) thereby camming the lock [14 downwardly and unlocking the bolt 46 from the battery position.

Operation After the insertion of magazine 23, loaded with double row of cartridges 102, into the magazine opening 22 .of :receiver 1'2 and secured therein by a latch 103, lock y14 then is angularly cammed downwardly out of slot `67 of bolt `46 by pressing forwardly on lever 9i) with the thumb of the left hand, such lever being on the left side of the rifle. The bolt .assembly f1'3 is then retracted to the rear by handle 132 permitting the uppermost cartridge 102 in the magazine 23 to enter the chambering space between the bolt 46 and the end of the bar-rel 77 whereby on the return of the bolt to the battery position, the round is chambered in the barrel and the gun 'is charged for tiring. After discharge of the cartridge 102 and when a conventional bullet yhas cleared the bore at the muzzle end (not shown) and while passing through the actuator, cup, (also not shown), the gases escaping from such bore impinge upon the inner wall of such cup that is coupled with lthe actuating bar 15 which in turn moves such bar forwardly thereby camming the lock 14 downwardly permitting `the bolt assembly 13 to recoil. When the bolt assembly 13 moves rearwardly in recoil, ejector '56 comes in contact with an ejector stop 104 secured to receiver Y12 and protruding into bore 2i) whereby ejector 56 stops in relation to the bolt 46 thereby ejecting spent cartridge 102 out of the receiver 12 through 4slot 31. At the end of the recoil strike, the bolt assembly 13 is returned to the battery position under the bias of spring 39 picking up the uppermost cartridge i102 from the magazine 23 and chambering same in the barrel. At the end of the counter-recoil cycle, actuating bar 1'5 moves lock '14 up into the locking position.

It will, therefore, be apparent to one skilled in the art that application of the principle of the invention disclosed herein provides novel and improved iirearm construction which is outstandingly characterized by a small number of parts with simplicity of configuration by such par-ts and also in cheapness of manufacture.

'I claim:

l. =In a iirearm having a receiver .and a bolt slidably mounted therein for reciprocal movement between a battery and a recoil position, the bolt having `a rrin-g pin tunnel axially therethrough and Lan intersecting vertical T-slot in the rear end thereof, a longitudinal tiring pin sl-idably sea-ted in said tunnel, a tiring pin retainer disposed in said T-slot and having a longitudinal hole therethrough coaxial with said tiring pin tunnel but of lesser diameter relative thereto, said tiring pin having a rear end portion of reduced diameter, spring means normally urging said tiring pin rearwardly into contact with the forward face of said retainer with said reduced end portion extending through said retainer 'to project beyond the rear face thereof, said retainer having a vertical slot extending along the underside thereof tto provide access to the rear wall surface for-med by said T-slot in the bolt, a bolt return slide having a substantially rectangular front end portion adapted to normally extend through said retainer slot into said T-slot to contact the bolt, spring means normally urging said bolt return slide forwardly -to maintain the bolt in the battery position thereof, `and striker means adapted Ito actuate said tiring pin forwardly when said bolt is in the battery position.

2. In a rearm having a receiver zand a bolt slidalbly mounted therein tor reciprocal movement between a battery and a recoil position, the bolt having a iiring pin tunnel axially therethrough and an intersecting T-slot extending vertically along the rear end thereof, a longitudinal firing pin slidably seated in said tunnel, a ring pin retainer disposed in `said T-slot land having fa longitudinal hole therethrough coaxial with said tiring pin tunnel but of lesser diameter relative thereto, said firing pin having a rear end portion of reduced diameter, spring means normally urging said iiring pin rearwardly into contact with the forward face of said retainer with said reduced end portion .of said tiring pin extending through said retainer to project beyond the rear face thereof, said retainer having a vertical slot .along the underside thereof to provide access to the rear wall surface formed by said T-slot, a longitudinal rod iixedly secured at either end in the receiver below the reciprocating path of the bo'lt, a bolt return slide comprising a body and an arm projecting forwardly from the upper end of said body, said arm having a substantially rectangular front end portion projecting upwardly therefrom and adapted to normally extend through said retainer slot in-to contact With the rear wall surface of said T-slot, said bolt Ireturn slide having a hole through the body thereof `for slidably receiving the forward end Iof said longitudinal rod therethrough, yspring means surrounding ysaid rod in abutment with the rear end of said bolt return slide body for normally urging said slide forwardly .to maintain the bolt in the battery position thereof, and a striker slida'bly disposed in the receiver in :axial alignment with said ring pin, said striker 'adapted to be released from la retracted position for Acontact with the rear end of said rin-g pin projecting beyond said tiring pin retainer in the battery position of the bolt whereby `said firing pin is actuated forwardly to discharge the firearm.

References Cited in the file of this patent UNITED STATES PATENTS [Reising July 8, 19i19 Kul-.ti June 28, 19'49 Williams Ian. ,10, 11950 Jensen Aug. 12, I19512 Lockhead I-an. 217, 195B 

